Ultrafast Spectroscopic Investigation of Energy Transfer
in Site-Directed Mutants of the Fenna–Matthews–Olson
(FMO) Antenna Complex from <i>Chlorobaculum tepidum</i>
Nikki
Cecil M. Magdaong
Rafael G. Saer
Dariusz M. Niedzwiedzki
Robert E. Blankenship
10.1021/acs.jpcb.7b01270.s001
https://acs.figshare.com/articles/journal_contribution/Ultrafast_Spectroscopic_Investigation_of_Energy_Transfer_in_Site-Directed_Mutants_of_the_Fenna_Matthews_Olson_FMO_Antenna_Complex_from_i_Chlorobaculum_tepidum_i_/4954151
Ultrafast
transient absorption (TA) and time-resolved fluorescence
(TRF) spectroscopic studies were performed on several mutants of the
bacteriochlorophyll (BChl) <i>a</i>-containing Fenna–Matthews–Olson
(FMO) complex from the green sulfur bacterium <i>Chlorobaculum
tepidum</i>. These mutants were generated to perturb a particular
BChl <i>a</i> site and determine its effects on the optical
spectroscopic properties of the pigment–protein complex. Measurements
conducted at 77 K under both oxidizing and reducing conditions revealed
changes in the dynamics of the various spectral components as compared
to the data set from wild-type FMO. TRF results show that under reducing
conditions all FMO samples decay with a similar lifetime in the ∼2
ns range. The oxidized samples revealed varying fluorescence lifetimes
of the terminal BChl <i>a</i> emitter, considerably shorter
than those recorded for the reduced samples, indicating that the quenching
mechanism in wild-type FMO is still present in the mutants. Global
fitting of TA data yielded similar overall results, and in addition,
the lifetimes of early decaying components were determined. Target
analyses of TA data for select FMO samples generated kinetic models
that better simulate the TA data. A comparison of the lifetime of
excitonic components for all samples reveals that the mutations affect
mainly the early kinetic components, but not that of the lowest energy
exciton, which reflects the flexibility of energy transfer in FMO.
2017-04-19 00:00:00
TA data
wild-type FMO
TRF results show
Chlorobaculum tepidum Ultrafast
component
BChl
FMO samples decay
Ultrafast Spectroscopic Investigation
sulfur bacterium Chlorobaculum tepidum
mutant
lifetime